The Mad Hatter suffers from mercury poisoning, a common and unfortunate condition peculiar to the hatters of Lewis Carroll's time. Hatters regularly used mercury to turn fur into felt, and thus breathed in the fumes of this highly toxic metal. For the 2010 Alice in Wonderland film, Johnny Depp and director Tim Burton heightened the Hatter’s madness by illustrating the character’s many mad mood swings in his makeup and wardrobe, creating a virtual human mood ring.